Method and device for generating parameter set for image encoding/decoding

ABSTRACT

A method of generating a parameter set includes obtaining common information inserted into at least two lower parameter sets which belong to the same upper parameter set; determining whether the common information is to be added to at least one among the upper parameter set and the at least two lower parameter sets; and adding the common information to at least one among the upper parameter set and the at least two lower parameter sets, based on a result of the determining.

RELATED APPLICATIONS

This application is a National Stage Entry of PCT InternationalApplication No. PCT/KR2014/000161, filed on Jan. 7, 2014, which claimsthe benefit of U.S. Provisional Application No. 61/749,467, filed onJan. 7, 2013, in the US Patent Office, and the disclosures of which areincorporated herein by reference in their entireties.

BACKGROUND

1. Field

Methods and apparatuses consistent with exemplary embodiments relate togenerating a parameter set to encode/decode an image.

2. Description of Related Art

Recently, as digital display technology has advanced and thehigh-quality digital TV age has come, new codec has been suggested toprocess a large amount of video data.

According to the High Efficiency Video Coding (HEVC) standards, anetwork abstraction layer (NAL) unit of encoded image data may includeparameter sets corresponding to header information. The parameter setsmay include a video parameter set (VPS), a sequence parameter set (SPS),a picture parameter set (PPS), etc.

Thus, much attention has been paid to methods of generating a parameterset and encoding or decoding an image in order to efficiently encode animage.

SUMMARY

Exemplary embodiments include a method and an apparatus for generating aparameter set to efficiently encode or decode image data.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of exemplary embodiments.

Exemplary embodiments may address at least the above problems and/ordisadvantages and other disadvantages not described above. Also,exemplary embodiments are not required to overcome the disadvantagesdescribed above, and an exemplary embodiment may not overcome any of theproblems described above.

According to an aspect of one or more exemplary embodiments, a method ofgenerating a parameter set includes obtaining common informationinserted into at least two lower parameter sets which belongs to thesame upper parameter set; determining whether the common information isto be added to at least one among the upper parameter set and the atleast two lower parameter sets; and adding the common information to atleast one among the upper parameter set and the at least two lowerparameter sets, based on a result of the determining.

The adding of the common information may include generating a first flagindicating that the common information is to be added to the upperparameter set or a second flag indicating that the common information isto be added to at least one among the at least two lower parameter sets,based on the result of the determining; and adding the generated flag tothe upper parameter set.

The adding the common information to at least one among the upperparameter set and the at least two lower parameter sets may includeadding information, to at least one lower parameter set, whichreferences the common information included in at least one among theupper parameter set and the at least two lower parameter sets, based onthe result of the determining.

The common information may include at least one among image formatinformation, bit depth information, resolution information, andthree-dimensional (3D) coding information of image data to be encoded.The upper parameter set may be a video parameter set (VPS). The at leasttwo lower parameter sets may be sequence parameter sets (SPSs). The SPSsmay be parameter sets referring to the VPS.

According to yet another aspect of one or more exemplary embodiments, amethod of decoding an image includes determining whether commoninformation of a lower parameter set is added to at least one among anupper parameter set and at least one lower parameter set; obtaining thecommon information of the lower parameter set by referring to at leastone among the upper parameter set and the at least one lower parameterset, based on a result of the determining; and decoding an imagecorresponding to the at least one lower parameter set based on theobtained common information.

The determining of whether the common information of the lower parameterset is added to at least one among the upper parameter set and the atleast one lower parameter set may include obtaining at least one among afirst flag indicating that the common information is added to the upperparameter set and a second flag indicating that the common informationis added to the at least one lower parameter set among the lowerparameter sets; and determining whether the common information is addedto the upper parameter set or the at least one lower parameter set,based on the at least one of the first and second flags.

The common information may include at least one among image formatinformation, bit depth information; resolution information; andthree-dimensional (3D) coding information of image data to be encoded.The upper parameter set may be a video parameter set (VPS). The at leastone lower parameter set may be a sequence parameter set (SPS). The SPSmay be a parameter set which belongs to the same VPS.

The decoding of the image corresponding to the at least one lowerparameter set may include performing session negotiation or selectingdata to be decoded, based on at least one among the image formatinformation, the bit depth information, the resolution information, andthe 3D coding information of the image data to be encoded; and decodingthe image based on a result of the performing session negotiation or theselecting data to be decoded.

According to yet another aspect of one or more exemplary embodiments, aparameter set generation apparatus includes a common informationobtainer configured to obtain common information commonly inserted intoat least two lower parameter sets which belong to the same upperparameter set; and a parameter set generator which determines whetherthe common information is to be added to at least one among the upperparameter set and the at least two lower parameter sets, and which addsthe common information to at least one among the upper parameter set andthe at least two lower parameter sets, based on a result of thedetermining.

According to an aspect of one or more exemplary embodiments, an imagedecoding apparatus includes a common information obtainer configured todetermine whether common information of a lower parameter set is addedto at least one among an upper parameter set and at least one lowerparameter set, and configured to obtain the common information of thelower parameter set with reference to at least one among the upperparameter set and the at least one lower parameter set, based on aresult of the determining; and an image decoder configured to decode animage corresponding to the at least one lower parameter set based on theobtained common information.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects will become apparent and more readilyappreciated from the following detailed description of exemplaryembodiments, taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a block diagram illustrating an internal structure a parameterset generation apparatus according to an exemplary embodiment;

FIG. 2 is a block diagram illustrating an internal structure of an imageencoding apparatus according to an exemplary embodiment;

FIGS. 3 and 4 are block diagrams illustrating internal structures ofimage decoding apparatuses according to exemplary embodiments;

FIG. 5 is a block diagram illustrating an internal structure of an imageencoder according to an exemplary embodiment;

FIG. 6 is a block diagram illustrating an internal structure of an imagedecoder according to an exemplary embodiment;

FIGS. 7 and 8 are flowcharts illustrating methods of generating aparameter set according to exemplary embodiments;

FIGS. 9 and 10 are flowcharts illustrating methods of decoding an imageaccording to exemplary embodiments;

FIG. 11 is a diagram illustrating a method of generating a parameter setaccording to an exemplary embodiment; and

FIGS. 12 to 14 are diagrams illustrating examples of parameters setsincluding syntax elements according to exemplary embodiments.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, exemplary embodiments will be described in detail withreference to the accompanying drawings. In the following disclosure andthe accompanying drawings, well-known functions or constructions are notdescribed and illustrated in detail if it is determined that they wouldobscure the invention due to unnecessary detail. Also, the same elementsare denoted by the same reference numerals throughout the drawings, ifpossible.

The terms or expressions used in the present specification and theclaims should not be construed as being limited to as generallyunderstood or as defined in commonly used dictionaries, and should beunderstood according to a technical field of exemplary embodiments,based on the principle that the inventor(s) of the application canappropriately define the terms or expressions to optimally explainexemplary embodiments. Thus, the exemplary embodiments set forth in thepresent specification and drawings are just examples and do notcompletely represent an inventive concept. Accordingly, it would beobvious to those of ordinary skill in the art that the above exemplaryembodiments are to cover all modifications, equivalents, andalternatives falling within the scope of an inventive concept at thefiling date of the present application.

It will be understood that the terms “comprises” and/or “comprising”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. Also, the terms “unit”, “module”, “component”, etc. mean unitsfor processing at least one function or operation and may be embodied ashardware, software, or a combination thereof.

The principle of exemplary embodiment is applicable to coding standardsbased on any intra-frames/inter-frames. Throughout the presentdisclosure, the term ‘image’ has been used as a comprehensive term tocover not only the term ‘image’ itself but also other various shapes ofvideo image information, such as a ‘frame’, a ‘field’, and a ‘slice’,which are known in the technical field to which exemplary embodimentspertain.

As used herein, expressions such as “at least one of,” when preceding alist of elements, modify the entire list of elements and do not modifythe individual elements of the list.

Exemplary embodiments will now be described with reference to theaccompanying drawings.

FIG. 1 is a block diagram illustrating an internal structure of aparameter set generation apparatus according to an exemplary embodiment;

A parameter set that may be used to encode or decode image data has beensuggested to prevent an error from occurring due to damage to a sequenceheader or a picture header. A sequence parameter set or a pictureparameter set may include identification information included in asequence header or a picture header, common syntax elements, imageinformation, etc. A video parameter set may include syntax elements orimage information that may be commonly used for the sequences of imagedata including a plurality of layers. The information included in eachof these parameter sets may be used to encode or decode an imagecorresponding to each image data.

In an exemplary embodiment, the sequence parameter set will be referredto as ‘SPS’, the picture parameter set will be referred to as ‘PPS’, andthe video parameter set will be referred to as ‘VPS’.

By referring to an upper parameter set of each parameter set,information included in the upper parameter set may be used to encode ordecode image data corresponding to each parameter set. For example, aPPS may refer to an SPS corresponding to a sequence to which a picturecorresponding to the PPS belongs, and an SPS may refer to a VPS ofscalable image data to which a sequence corresponding to the SPSbelongs. Thus, information in the upper parameter set may be obtainedand used to encode or decode an image corresponding to the PPS or theSPS.

In the following exemplary embodiment, an upper parameter set may be aparameter set that may be referred to by a lower parameter set. Forexample, a VPS may be an upper parameter set of an SPS, and an SPS maybe an upper parameter set of a PPS.

Referring to FIG. 1, the parameter set generation apparatus 100 mayinclude a common information obtainer 110 and a parameter set generator120, which may be embodied as hardware, software, or a combinationthereof. However, all of the elements of the parameter set generationapparatus 100 illustrated in FIG. 1 are not indispensable elements. Theparameter set generation apparatus 100 may further include otherelements or may include only one of these elements.

These elements according to an exemplary embodiment will be describedbelow.

The common information obtainer 110 may obtain common informationcommonly inserted into at least two lower parameter sets referring tothe same upper parameter set.

In the following description of exemplary embodiments, that informationis inserted into a parameter set should be understood as that theinformation is to be added to the parameter set or that the informationis added to the parameter set but may not be encoded in an encodingprocess. Also, that the information is added to the parameter set shouldbe understood as that the information is added to the parameter set soas to be encoded.

The common information may include information commonly included in twoor more parameter sets of the same rank. For example, the commoninformation obtainer 110 may obtain common information commonly insertedinto two or more SPSs referring to the same VPS.

According to an exemplary embodiment, the common information may includeat least one among image format information, bit depth information,resolution information, and three-dimensional (3D) coding information ofimage data to be encoded. The information described above may beincluded in an upper parameter set to be processed earlier than a lowerparameter set and may be thus used to perform session negotiation orcontents selection (which will be described below) during an imagedecoding process. The session negotiation or the contents selection willbe described in detail when an image decoding apparatus 300 is describedbelow.

The parameter set generator 120 may add the common information obtainedby the common information obtainer 110 to an upper parameter set or toat least one lower parameter set among lower parameter sets includingthe common information. Thus, common information of a lower parameterset may be obtained by referring to an upper parameter set or the atleast one upper parameter set to which the common information is added.

Thus, according to an exemplary embodiment, common information that maybe redundantly added to at least two lower parameter sets may be addedto an upper parameter set or at least one lower parameter set.Accordingly, the common information may be prevented from beingredundantly added to two or more lower parameter sets, therebyminimizing the amount of information to be encoded.

The common information of two or more lower parameter sets into whichthe common information was inserted may be obtained by referring to theupper parameter set or the at least one lower parameter set to which thecommon information is added during a subsequent decoding process.

FIG. 2 is a block diagram illustrating an internal structure of an imageencoding apparatus according to an exemplary embodiment.

Referring to FIG. 2, the image encoding apparatus 200 may include acommon information obtainer 210, a parameter set generator 220, an imageencoder 230, and an outputter 240, which may be embodied as hardware,software, or a combination thereof. The common information obtainer 210and the parameter set generator 220 of FIG. 2 correspond to or areanalogous to the common information obtainer 110 and the parameter setgenerator 120 of FIG. 1, respectively. Thus, descriptions of the commoninformation obtainer 210 and the parameter set generator 220 that arerespectively the same as those of the common information obtainer 110and the parameter set generator 120 are omitted here. The elements ofthe image encoding apparatus 200 illustrated in FIG. 2 are, however, notindispensable elements. The image encoding apparatus 200 may furtherinclude other elements or may include only some of the elements.

These elements will be described below according to an exemplaryembodiment.

The common information obtainer 210 may obtain common informationcommonly inserted into at least two lower parameter sets referring tothe same upper parameter set. The common information may includeinformation commonly included in two or more parameter sets of the samerank. For example, the common information obtainer 210 may obtain commoninformation commonly inserted into two or more SPSs or PPSs referring tothe same VPS.

The parameter set generator 220 may add the common information obtainedby the common information obtainer 210 to an upper parameter set or atleast one lower parameter set among lower parameter sets including thecommon information.

The parameter set generator 220 may include a flag generator 221 togenerate a flag indicating whether the common information is includedand to add the flag to a parameter set. At least one flag among a flagindicating whether the common information is to be added to the upperparameter set and a flag indicating whether the common information is tobe added to the at least one lower parameter set may be added to theupper parameter set or a lower parameter set to which the commoninformation is added.

For example, both the two flags described above may be included in theupper parameter set. Also, the flag indicating whether the commoninformation is to be added to the at least one lower parameter set maybe added to the lower parameter sets to which the common information isadded.

Furthermore, a parameter set for obtaining common information byreferring to another parameter set may include information for referringto the other parameter set.

The image encoder 230 may encode an image, based on common informationor a flag added by the parameter set generator 220.

The outputter 240 may output a bitstream containing the image encoded bythe image encoder 230 and information needed to decode the image, i.e.,a bitstream containing a plurality of parameter sets.

FIG. 3 is a block diagram illustrating an internal structure of an imagedecoding apparatus 300 according to an exemplary embodiment. FIG. 4 is ablock diagram illustrating an internal structure of an image decodingapparatus 400 according to another exemplary embodiment.

Referring to FIG. 3, the image decoding apparatus 300 may include acommon information obtainer 310 and an image decoder 320, which may beembodied as hardware, software, or a combination thereof. However, allof these elements are not indispensable elements. The image decodingapparatus 300 may further include other elements or only one of theseelements.

These elements will be described below, according to an exemplaryembodiment.

The common information obtainer 310 may obtain common information froman upper parameter set or a lower parameter set according to whethercommon information of at least one lower parameter set is added to theupper parameter set or the lower parameter set.

The image decoder 320 may decode an image based on the commoninformation obtained by the common information obtainer 310.

According to an exemplary embodiment, the common information that may beadded to the upper parameter set may include at least one among imageformat information, bit depth information, resolution information, and3D coding information of image data to be encoded as described above.

The image format information may contain information regarding an imageformat of a current image. For example, the image format may be 4:4:4 or4:2:2.

The bit depth information may include information regarding a bit depthindicating the number of bits that represent color values of pixels ofan image.

The resolution information may include information regarding the numberof pixels per width or height of the image.

The 3D coding information may include at least one of informationindicating whether the current image is frame-packed and informationindicating whether the current image has an interlaced video format.Frame packing information may indicate whether left and right imagesthat constitute a 3D image are formatted and encoded in one imageformat. Interlaced information indicates whether the left and rightimages are encoded such that the left and right images are interlacedwhen the frame packing information indicates that the left and rightimages are formatted in one image format.

The information described above may be included in an upper parameterset, which may be processed earlier than a lower parameter set, to beused for session negotiation or contents selection during an imagedecoding process.

The session negotiation may include an operation for determining data tobe received from an external device beforehand so that data needed forthe image decoding apparatus 300 to decode an image or data that may bedecoded by the image decoding apparatus 300 may be selectively received.In this case, the external device is a device configured to transmitencoded image data to the image decoding apparatus 300, and may be animage encoding apparatus or an apparatus storing the encoded image data.

For example, the image decoding apparatus 300 may select image dataneeded for the image decoding apparatus 300 to decode an image andreceive the image data from the external device, based on at least oneamong the image format information, the bit depth information, theresolution information, and the 3D coding information. For example, whenthe image decoding apparatus 300 cannot reproduce a 3D image, the 3Dimage or information needed to encode the 3D image may not be needed.Thus, through the session negotiation, the image decoding apparatus 300may determine not to receive a 3D image or information needed to encodethe 3D image but to receive a two-dimensional (2D) image or informationneeded to encode the 2D image.

Thus, the common information described above according to an exemplaryembodiment may be obtained earlier than a bitstream containing encodedimage data, thereby enabling the image decoding apparatus 300 to selectimage data to be received, based on the common information.

Furthermore, the image decoding apparatus 300 may select content basedon the common information described above. That is, the image decodingapparatus 300 may select image data needed to decode an image, based onthe common information. For example, the image decoding apparatus 300may select and decode image data for decoding an image, based on atleast one among the image format information, the bit depth information,the resolution information, and the 3D coding information.

Accordingly, the common information described above according to anexemplary embodiment may be obtained earlier than a bitstream containingencoded image data, and the image decoding apparatus 300 may thus selectimage data to be encoded based on the common information before theimage data is decoded. Also, the image decoding apparatus 300 may decodeimage data selected based on the common information.

Referring to FIG. 4, the image decoding apparatus 400 may include areceiver 410, a flag obtainer 420, a common information obtainer 430,and an image decoder 440, which may be embodied as hardware, software,or a combination thereof. The common information obtainer 430 and theimage decoder 440 of FIG. 4 correspond or are analogous to the commoninformation obtainer 310 and the image decoder 320 of FIG. 3,respectively. Descriptions of the common information obtainer 430 andthe image decoder 440 that are respectively the same as those of thecommon information obtainer 310 and the image decoder 320 are omittedhere. All of the elements of the image decoding apparatus 400illustrated in FIG. 4 are not indispensable elements. The image decodingapparatus 400 may further include other elements or may include onlysome of these elements.

The elements of the image decoding apparatus 400 will be describedbelow, according to an exemplary embodiment.

The receiver 410 may receive and parse a bitstream containing an encodedimage.

The flag obtainer 420 may receive a flag indicating whether commoninformation is included in at least one of an upper parameter set and alower parameter set from the parsed bitstream. At least one lowerparameter set may receive the common information by referring to theupper parameter set or the lower parameter set, based on the flag. Thatis, when an image corresponding to the at least one lower parameter setis to be decoded, the image decoding apparatus 400 may obtain commoninformation by referring to the upper parameter set or the lowerparameter set containing the common information.

The common information obtainer 430 may receive the common informationfrom the upper parameter set or the lower parameter set, based on theflag obtained by the flag obtainer 420. In this case, the image decodingapparatus 400 may receive the common information from the upperparameter set or the lower parameter set by using reference informationcontained in a current parameter set.

The image decoder 440 may decode image data corresponding to the currentparameter set, based on the common information obtained by the commoninformation obtainer 430.

FIG. 5 is a block diagram illustrating an internal structure of an imageencoder according to an exemplary embodiment.

Referring to FIG. 5, the image encoder 500 according to an exemplaryembodiment may include a motion estimator 501, a motion compensator 502,an intra-predictor 503, a transformer 505, a quantization component 506,an entropy encoder 507, an inverse quantization component 508, aninverse transformer 509, a deblocker 510, and a loop filter 511, whichmay be embodied as hardware, software, or a combination thereof. Theimage encoder 500 of FIG. 5 may correspond or be analogous to the imageencoder 230 of FIG. 2.

The motion estimator 501 may estimate the motion of a current image,which is currently input from the outside, by using reference imagesbelonging to an RPS for the current image among images constitutingvideo.

The motion compensator 502 may produce a predicted image of the currentimage from the reference images belonging to the RPS for the currentimage. More specifically, the motion compensator 502 may produce apredicted image of the current image, based on the motion of the currentimage estimated by the motion estimator 501.

The intra-predictor 503 may produce a predicted image of the currentimage by predicting blocks corresponding to an intra mode among blocksthat constitute the current image.

The transformer 505 may transform a residual image, which is obtained bysubtracting a predicted image from the current image, from a spatialdomain to a frequency domain. For example, the transformer 505 maytransform the residual image from the spatial domain to the frequencydomain by performing integer transformation such as Discrete HadamardTransform (DHT), Discrete Cosine Transform (DCT), etc.

The quantization component 506 may quantize results of transformationperformed by the transformer 505.

The entropy encoder 507 may generate a bitstream by entropy-encodingresults of quantization performed by the quantization component 506. Inparticular, the entropy encoder 507 may entropy-encode not only theresults of quantization performed by the quantization component 506 butalso information for decoding video, e.g., RPS information used toperform inter prediction, motion vector information, locationinformation of neighboring blocks used to perform intra prediction, etc.

The inverse quantization component 508 may inversely quantize theresults of quantization performed by the quantization component 506.

The inverse transformer 509 may restore a residual image between thecurrent image and a predicted image by transforming results of inversequantization performed by the inverse quantization component 508, i.e.,transform coefficients, from a frequency domain to a spatial domain.

The deblocker 510 and the loop filter 511 may perform adaptive filteringon an image restored by the inverse quantization component 508.

FIG. 6 is a block diagram illustrating an internal structure of an imagedecoder according to an exemplary embodiment.

Referring to FIG. 6, the image decoder 600 according to an exemplaryembodiment may include a parser 601, an entropy-decoder 603, an inversequantization component 605, an inverse transformer 607, anintra-predictor 609, a deblocker 611, a loop filter 613, and a motioncompensator 615, which may be embodied as hardware, software, or acombination thereof. The image decoder 600 of FIG. 6 may correspond orbe analogous to the image decoder 320 of FIG. 3 and the image decoder440 of FIG. 4.

The parser 601 may parse a bitstream to extract encoded image data to bedecoded and coding information for decoding the encoded image data fromthe bitstream.

The entropy decoder 603 may entropy-decode the bitstream to restoreinformation for decoding video.

The inverse quantization component 605 may inversely quantize valuesrestored by the entropy decoder 603 to restore transform coefficients.

The inverse transformer 607 may transform the transform coefficientsrestored by the inverse quantization component 602 from a frequencydomain to a spatial domain to restore a residual image between a currentimage and a predicted image.

The intra-predictor 609 may produce a predicted image of the currentimage by predicting the values of blocks of the current image from thevalues of restored blocks adjacent to the blocks of the current imageamong blocks of the current image that are restored for blockscorresponding to an intra-mode among blocks that constitute the currentimage. A restored image may be produced by adding a residual image tothe predicted image.

The motion compensator 615 may produce a predicted image of the currentimage from reference images included in an RPS to be used toprediction-decode the current image. A restored image may be produced byadding a residual image to the predicted image.

The deblocker 611 and the loop filter 613 may adaptively filter arestored image.

Methods of encoding or decoding an image, according to exemplaryembodiments, will be described in more detail with reference to FIGS. 7to 10 below.

FIGS. 7 and 8 are flowcharts illustrating methods of generating aparameter set according to exemplary embodiments.

Referring to FIG. 7, in operation S701, the parameter set generationapparatus 100 may obtain common information commonly inserted into atleast two lower parameter sets referring to the same upper parameterset. In an exemplary embodiment, the parameter set generation apparatus100 may encode common information commonly inserted into two or morelower parameter sets by adding the common information to the upperparameter set so that the common information may be signaled only once.

In operation S703, the parameter set generation apparatus 100 maydetermine whether the common information obtained in operation S701 isto be added to at least one of the upper parameter set and at least onelower parameter set. Specifically, the parameter set generationapparatus 100 may determine whether the common information is to beredundantly added to two or more lower parameter sets or is to be addedto the upper parameter set or a lower parameter set so that the commoninformation may be signaled only once without adding the commoninformation to other parameter sets.

A lower parameter set to which the common information is to be added maybe, for example, an SPS for image data of a base layer. Thus, theparameter set generation apparatus 100 may add the common informationobtained in operation S701 to the SPS for the image data of the baselayer and add reference information to an SPS for image data of anotherlayer so that the SPS may refer to the SPS of the base layer.

In operation S705, the parameter set generation apparatus 100 may addthe common information to at least one of the upper parameter set andthe at least one lower parameter set, based on a result of thedetermining in operation S703. Thus, a lower parameter set, includingthe common information, may obtain the common information by referringto the upper parameter set or the at least one lower parameter setduring a decoding process. Accordingly, the common information may beencoded not to be redundantly signaled in the two or more lowerparameter sets.

Referring to FIG. 8, the image encoding apparatus 200 may determinewhether common information is to be added to an upper parameter set orat least one lower parameter set, based on a flag, unlike in the methodof FIG. 7.

Referring to FIG. 8, in operation S801, the image encoding apparatus 200may obtain common information commonly inserted into at least two lowerparameter sets referring to the same upper parameter set.

In operation S803, the image encoding apparatus 200 may determinewhether the common information is to be added to the upper parameter setof at least two lower parameter sets to which the common informationobtained in operation S801 is to be inserted.

However, when the common information includes at least one among imageformat information, bit depth information, resolution information, and3D coding information of image data to be encoded, the image encodingapparatus 200 may add the common information to the upper parameter set.Before a lower parameter set or the image data is received or parsed,the session negotiation or contents selection may be performed by addinginformation for session negotiation or contents selection to the upperparameter set.

In operation S805, when it is determined in operation S803 that thecommon information is not to be added to the upper parameter set, theimage encoding apparatus 200 may determine whether the commoninformation obtained in operation S801 is to be added to at least onelower parameter set.

In operation S807, when the common information obtained in operationS801 is added to at least one lower parameter set, the image encodingapparatus 200 may generate a flag indicating this fact. That is, theimage encoding apparatus 200 may generate a flag indicating that thecommon information is not added to the upper parameter set but is addedto at least one lower parameter set. When the common information isadded to the at least one lower parameter set, a lower parameter setthat does not contain the common information may obtain the commoninformation by referring to the at least one lower parameter setcontaining the common information during a decoding process. To thisend, in an exemplary embodiment, the image encoding apparatus 200 mayadd information for referring to the at least one lower parameter setcontaining the common information to the lower parameter set.Furthermore, the image encoding apparatus 200 may generate a flagindicating that the common information is not added to the upperparameter set.

When the common information is added to at least one lower parameter setinstead of the upper parameter set, the data size of the upper parameterset may be prevented from increasing due to the addition of the commoninformation, and the common information may be prevented from beingredundantly encoded several times. When the data size of the upperparameter set increases, performing of the session negotiation orcontents selection may be delayed, thus lowering an encoding/decodingefficiency. Thus, the image encoding apparatus 200 may add the commoninformation to the at least one lower parameter set instead of the upperparameter set, in consideration of a delay in the session negotiation orcontents selection caused when the data size of the upper parameter setincreases.

In operation S809, the image encoding apparatus 200 may add the flaggenerated in operation S807 and the common information to the at leastone lower parameter set determined in operation S805. Furthermore, theflag generated in operation S807 may be added to the upper parameterset, considering that the upper parameter set is to be processed earlierthan lower parameter sets. The flag that may be added to the upperparameter set may include at least one of a flag indicating whether thecommon information is to be added to the upper parameter set and a flagindicating whether the common information is to be added to the at leastone lower parameter set. Furthermore, the image encoding apparatus 200may generate a parameter set and encode an image based on the parameterset.

In operation S811, when in operation S803, the image encoding apparatus200 determines that the common information is to be added to the upperparameter set, the image encoding apparatus 200 may generate a flagindicating that the common information is to be added to the upperparameter set. In addition, the image encoding apparatus 200 maygenerate a flag indicating whether the common information is to be addedto a lower parameter set. The image encoding apparatus 200 may addreference information to the lower parameter set so as to obtain thecommon information of the lower parameter set by referring to the upperparameter set.

When the common information is added to the upper parameter set, theimage encoding apparatus 200 may not add the common information to alower parameter set, but exemplary embodiment is not limited thereto andthe image encoding apparatus 200 may add the common information to thelower parameter set.

In operation S813, the image encoding apparatus 200 may add the flaggenerated in operation S811 and the common information to the upperparameter set. In addition, the image encoding apparatus 200 maygenerate a parameter set and encode an image based on the parameter set.

Furthermore, when it is determined in operation S805 that the commoninformation is not to be added to the at least one lower parameter set,the image encoding apparatus 200 may redundantly add the commoninformation to the two or more parameter sets to which the commoninformation is inserted in operation S801.

FIGS. 9 and 10 are flowcharts illustrating methods of decoding an image,according to exemplary embodiments.

Referring to FIG. 9, in operation S901, the image decoding apparatus 300may determine whether common information of at least two lower parametersets referring to the same upper parameter set is added to the upperparameter set or a lower parameter set.

In operation S903, the image decoding apparatus 300 may obtain thecommon information of a lower parameter set by referring to at least oneof the upper parameter set and the lower parameter set, based on theresults of determined performed in operation S901.

In operation S905, the image decoding apparatus 300 may decode imagedata corresponding to the lower parameter set obtaining the commoninformation from another parameter set by using the common informationobtained in operation S903.

In addition, when the common information includes at least one amongimage format information, bit depth information, resolution information,and 3D coding information of encoded image data and is added to an upperparameter set, the image decoding apparatus 300 may perform sessionnegotiation or contents selection based on the information describedabove.

Referring to FIG. 10, in operation S1001, the image decoding apparatus400 may determine whether common information of at least two lowerparameter sets referring to the same upper parameter set is added to anupper parameter set or a lower parameter set.

In operation S1003, the image decoding apparatus 400 may determinewhether the common information is added to the upper parameter set. Theimage decoding apparatus 400 may determine whether the commoninformation is added to the upper parameter set, based on a flag addedto the upper parameter set.

In operation S1005, the image decoding apparatus 400 may obtain thecommon information of the two or more lower parameter sets from theupper parameter set, based on the determination performed in operationS1003. In operation S1013, the image decoding apparatus 400 may decodean image based on the common information.

In operation S1007, the image decoding apparatus 400 may determinewhether the common information is added to at least one lower parameterset. The image decoding apparatus 400 may determine whether the commoninformation is added to at least one lower parameter set, based on aflag added to the upper parameter set or a lower parameter set.

In operation S1009, the image decoding apparatus 400 may obtain thecommon information of the at least two lower parameter sets from atleast one lower parameter set i.e., first lower parameter set accordingto the determination performed in operation S1007.

In addition, in operation S1011, when it is determined in operationS1007 that the common information is not added to at least one lowerparameter set, the common information may not be present for at leasttwo lower parameter sets or may be redundantly added to at least twolower parameter sets. Thus, when information needed to decode the imageis obtained from each of lower parameter sets, the image decodingapparatus 400 may not refer to the upper parameter set or at least onelower parameter set so as to obtain the common information. The imagedecoding apparatus 400 may obtain the information needed to decode theimage from current lower parameter set.

In operation S1013, the image decoding apparatus 400 may decode imagedata for a desired lower parameter set by using the information obtainedin operations S1005, S1009, and S1011.

FIG. 11 is a diagram illustrating a method of generating a parameterset, according to an exemplary embodiment.

In FIG. 11, referring to a diagram 1110, a VPS 1, and an SPS 1 to an SPSN referring to the VPS 1 may be present, according to an exemplaryembodiment. In this case, according to an exemplary embodiment, whenthere is information commonly included in the SPS 1, the SPS 2, and theSPS 3, each of these parameter sets may be reconfigured from the diagram1110 to a diagram 1120 or a diagram 1130.

Referring to the diagram 1120, common information included in the SPS 1,the SPS 2, and the SPS 3 is also included in the VPS 1. Thus, the commoninformation included in the VPS 1 may be encoded once withoutredundantly encoding the common information included in at least twoSPSs among the SPS1 to the SPS3, thereby improving the efficiency ofencoding the common information. The common information of the SPS 1,the SPS 2, and the SPS 3 may be obtained by referring to the VPS 1during a decoding process.

Referring to the diagram 1130, common information included in the SPS 2and the SPS 3 is also included in the SPS 1. Thus, the commoninformation included in the SPS 1 may be encoded once withoutredundantly encoding the common information included in at least twoSPSs, thereby improving the efficiency of encoding the commoninformation. In addition, referring to the diagram 1130, although thecommon information is added, the data size of the VPS 1 does notincrease, unlike in the diagram 1120. The SPS 2 and the SPS 3 may obtainthe common information by referring to the SPS 1 during a decodingprocess.

FIGS. 12 to 14 are diagrams illustrating examples of parameters setsincluding syntax elements, according to exemplary embodiments.

FIG. 12 illustrates a VPS as an example of an upper parameter setaccording to an exemplary embodiment.

Referring to FIG. 12, a vps_extension 1210 may include avps_sps_common_syntax_present_flag 1220 and avps_sps_interlayer_prediction_enable_flag 1230 that indicate whethercommon information is included in an upper parameter set or a lowerparameter set.

The vps_sps_common_syntax_present_flag 1220 is a flag indicating whethercommon information of lower parameter sets is included in the upperparameter set. For example, the vps_sps_common_syntax_present_flag 1220may have a value of ‘1’ when the common information is included in theupper parameter set, and may have a value of ‘0’ when the commoninformation is not included in the upper parameter set.

The vps_sps_interlayer_prediction_enable_flag 1230 is a flag indicatingwhether common information of lower parameter sets is included in onelower parameter set. In this case, the lower parameter set including thecommon information may be a lower parameter set corresponding to imagedata of a base layer. For example, thevps_sps_interlayer_prediction_enable_flag 1230 may have a value of ‘1’when the common information is included in the lower parameter set, andmay have a value of ‘0’ when the common information is not included inthe lower parameter set.

An interlayer_sps_prediction_flag[i] 1232 is a flag indicating thatcommon information of an SPS corresponding to image data of an i^(th)layer may be obtained by referring to an SPS containing the commoninformation. For example, the common information of the SPScorresponding to the image data of the i^(th) layer may be obtained byreferring to an SPS containing the common information when theinterlayer_sps_prediction_flag[i] 1232 has a value of ‘1’. Informationfor each of SPSs may be independent information that does not need torefer to other SPSs of different layers when theinterlayer_sps_prediction_flag[i] 1232 has a value of ‘0’.

An sps_prediction_ref_layer_id[i] 1234 is a syntax indicating an SPS ofa layer that includes the common information of the SPS corresponding tothe image data of the i^(th) layer.

When an if(!vps_sps_common_syntax_present_flag) 1221 indicates thecommon information is not included in the upper parameter set, whetherthe common information is included in a lower parameter set may bedetermined based on the vps_sps_interlayer_prediction_enable_flag 1230.

An if(vps_sps_interlayer_prediction_enable_flag) 1231 may indicatewhether common information of each of the SPSs is to be obtained byreferring to another SPS based on thevps_sps_interlayer_prediction_enable_flag 1230 and indicate an SPScontaining the common information for each of the SPSs, in the syntaxes1232 to 1234.

An if(vps_sps_common_syntax_present_flag) 1240 may indicate commoninformation that each of the SPSs may obtain by referring to another SPSbased on the vps_sps_common_syntax_present_flag 1220, in syntaxes 1241to 1243.

FIG. 13 illustrates a SPS as an example of a lower parameter setaccording to an exemplary embodiment.

A seq_parameter_set_rbsp 1310 may include an if(!vps_sps_common_syntax_present_flag∥layer_id==0∥interlayer_sps_prediction_flag[i]==0)1320, and various types of information 1330 for encoding/decoding animage.

When theif(!vps_sps_common_syntax_present_flag∥layer_id==0∥interlayer_sps_prediction_flag[i]==0)1320 indicates that common information is not included in the VPS or acurrent SPS is either an SPS corresponding to image data of a base layerwhich is a layer 0 or an SPS that is an independent SPS that is notreferred to by an SPS corresponding to image data of an i^(th) layer,the various types of information 1330 included in an if-clause may beincluded in the current SPS and encoded. The various types ofinformation 1330 included in the if-clause may be common informationobtained by referring to another SPS.

FIG. 14 illustrates a VPS as an example of an upper parameter setaccording to another exemplary embodiment.

Syntaxes 1420 may include various types of information that may be usedfor the image decoding apparatus 300 to perform session negotiation orcontents selection.

Specifically, vps_chroma_format_idc may correspond to the image formatinformation described above and have a value of ‘0’, ‘1’, ‘2’, or ‘3’.

vps_pic_width_in_luma_samples and vps_pic_height_in_luma_samples maycorrespond to the resolution information described above and have aninteger value. vps_pic_width_in_luma_samples may indicate the number ofpixels of a decoded image in a horizontal direction.vps_pic_height_in_luma_samples may indicate the number of pixels of thedecoded image in a vertical direction.

vps_bit_depth_luma_minus8 and vps_bit_depth_chroma_minus8 may correspondto the bit depth information described above. vps_bit_depth_luma_minus8and vps_bit_depth_chroma_minus8 may indicate bit depth information of aluma sample and bit depth information of a chroma sample, respectively,and have a value of ‘0’, ‘1’, ‘2’, ‘3’, ‘4’, ‘5’, or ‘6’.

vps_frame_packed_flag may correspond to the above-described framepacking information indicating whether a current image is frame-packed.vps_interlaced_flag may correspond to the above-described interlaceinformation indicating whether the current image has an interlaced videoformat. vps_frame_packed_flag and vps_interlaced_flag may have a valueof ‘0’ or ‘1’. vps_interlaced_flag is based on a premise that thecurrent image is frame-packed and may thus have a value of ‘1’ when thevps_frame_packed_flag has a value of ‘1’. That is, vps_interlaced_flagalways has a value of ‘0’ when the vps_frame_packed_flag has a value of‘0’, and may have a value of ‘0’ or ‘1’ when the vps_frame_packed_flaghas a value of ‘1’.

The various types of information described above may be included in anupper parameter set that may be processed earlier than a lower parameterset and may be thus used to perform session negotiation or contentsselection during an image decoding process.

According to an exemplary embodiment, an image may be efficientlyencoded or decoded by removing information that is redundantly includedin parameter sets.

According to an exemplary embodiment, information included in a lowerparameter set and is needed to perform session negotiation may beincluded in an upper parameter set so that session negotiation may beperformed when the upper parameter set is processed.

A method according to an exemplary embodiment can be embodied ascomputer readable code in computer readable recoding media (includingvarious devices having an information processing function). The computerreadable recording media include various types of recording apparatusescapable of storing data that is read by a computer system, e.g.,read-only memory (ROM), random access memory (RAM), a compact disc(CD)-ROM, a magnetic tape, a floppy disk, an optical data storagedevice, and so on.

Although novel characteristics that are applicable to various exemplaryembodiments have been focused in the present disclosure, it would beobvious to those of ordinary skill in the art that the above exemplaryembodiments are to cover all modifications, equivalents, andalternatives falling within the scope of inventive concept. Accordingly,it will be understood that various changes in form and details may bemade therein without departing from the spirit and scope of thefollowing claims and their equivalents.

What is claimed is:
 1. A method of generating a parameter set, themethod comprising: obtaining common information inserted into at leasttwo lower parameter sets that refer to the same upper parameter set;determining whether the common information is to be added to at leastone among the upper parameter set and the at least two lower parametersets; generating a first flag indicating that the common information isto be added to the upper parameter set or a second flag indicating thatthe common information is to be added to at least one among the at leasttwo lower parameter sets, based on a result of the determining; addingthe generated first or second flag to the upper parameter set; andadding the common information to at least one among the upper parameterset and the at least two lower parameter sets based on the added firstor second flag.
 2. The method of claim 1, wherein the adding the commoninformation to at least one among the upper parameter set and the atleast two lower parameter sets comprises adding, to at least one lowerparameter set, information which references the common informationincluded in at least one among the upper parameter set and the at leasttwo lower parameter sets, based on the result of the determining.
 3. Themethod of claim 1, wherein: the common information comprises at leastone among image format information, bit depth information, resolutioninformation, and three-dimensional (3D) coding information of image datato be encoded, the upper parameter set is a video parameter set (VPS),the at least two lower parameter sets are sequence parameter sets(SPSs), and the SPSs are parameter sets which refer to the VPS.
 4. Amethod of decoding an image, the method comprising: obtaining at leastone among a first flag indicating whether common information of a lowerparameter set is added to an upper parameter set and a second flagindicating whether the common information is added to at least one lowerparameter set among lower parameter sets; determining whether commoninformation is added to at least one among the upper parameter set andthe at least one lower parameter set, based on the at least one of thefirst flag and the second flag; obtaining the common information of thelower parameter set by referring to at least one among the upperparameter set and the at least one lower parameter set, based on aresult of the determining; and decoding an image corresponding to the atleast one lower parameter set based on the obtained common information.5. The method of claim 4, wherein: the common information comprises atleast one among image format information; bit depth information;resolution information; and three-dimensional (3D) coding information ofimage data to be encoded, the upper parameter set is a video parameterset (VPS), the at least one lower parameter set is a sequence parameterset (SPS), and the SPS is a parameter set which refers to the VPS. 6.The method of claim 5, wherein the decoding the image corresponding tothe at least one lower parameter set comprises: performing sessionnegotiation or selecting data to be decoded, based on at least one amongthe image format information, the bit depth information, the resolutioninformation, and the 3D coding information of the image data to beencoded; and decoding the image based on a result of the performingsession negotiation or the selecting data to be decoded.
 7. A parameterset generation apparatus comprising: a common information obtainerconfigured to obtain common information inserted into at least two lowerparameter sets which refer to the same upper parameter set; and aparameter set generator configured to determine whether the commoninformation is to be added to at least one among the upper parameter setand the at least two lower parameter sets, generate a first flagindicating that the common information is to be added to the upperparameter set or a second flag indicating that the common information isto be added to at least one among the at least two lower parameter sets,based on a result of the determining, and configured to add the commoninformation to at least one among the upper parameter set and the atleast two lower parameter sets, based on the added first or second flag.8. The parameter set generation apparatus of claim 7, wherein theparameter set generator adds, to the at least one lower parameter set,information which references the added common information, based on theresult of the determining.
 9. The parameter set generation apparatus ofclaim 7, wherein: the common information comprises at least one amongimage format information, bit depth information; resolution information,and three-dimensional (3D) coding information of image data to beencoded, the upper parameter set is a video parameter set (VPS), thelower parameter sets are sequence parameter sets (SPSs), and the SPSsare parameter sets which refers to the VPS.
 10. An image decodingapparatus comprising: a flag obtainer configured to obtain at least oneamong a first flag indicating that common information of a lowerparameter set is added to an upper parameter set and a second flagindicating that the common information is added to at least one lowerparameter set, a common information obtainer configured to determinewhether the common information of the lower parameter set is added to atleast one among the upper parameter set and the at least one lowerparameter set based on the at least one of the first flag and the secondflag, and configured to obtain the common information of the lowerparameter set by referring to at least one among the upper parameter setand the at least one lower parameter set, based on a result of thedetermining; and an image decoder configured to decode an imagecorresponding to the at least one lower parameter set based on theobtained common information.
 11. The image decoding apparatus of claim10, wherein: the common information comprises at least one among imageformat information, bit depth information, resolution information, andthree-dimensional (3D) coding information of image data to be encoded,the upper parameter set is a video parameter set (VPS), the at least onelower parameter set is a sequence parameter set (SPS), and wherein theSPS is a parameter set which refers to the VPS.
 12. The image decodingapparatus of claim 10, wherein the image decoder is configured toperform session negotiation or select data to be decoded, based on atleast one among image format information, bit depth information,resolution information, and the 3D coding information of the image datato be encoded, and configured to decode the image based on a result ofthe performing session negotiation or the selecting data to be decoded.13. The method of claim 1, wherein the at least two lower parameter setsand the upper parameter set corresponds to header information of anetwork abstraction layer of image data encoded with a high efficiencyvideo coding standard.
 14. The method of claim 1, further comprisingadding, to the upper parameter set, the first flag which indicateswhether the common information of the at least two lower parameter setsis included in the upper parameter set and the second flag whichindicates that the common information of the at least two lowerparameter sets is included in one of the two lower parameter sets. 15.The method of claim 1, wherein the common information comprises at leastone of image format information, bit depth information, resolutioninformation, a three-dimensional coding information and wherein thedetermining comprises determining to which one parameter set to add thecommon information from among the upper parameter set and the at leasttwo lower parameter sets.
 16. The method of claim 1, wherein the commoninformation is added to one of the upper parameter set and one of the atleast two lower parameter sets and wherein the common informationcomprises information related to at least one of a session negotiationand a selection of contents during decoding of the contents.